While using an AMD Barcelona server to create a portable benchmarking kit, InfoWorld's Tom Yager discovered something unexpected: "I could incur variances in some benchmark tests ranging from 10 to 60 percent through combined manipulation of the server's BIOS settings, BIOS version, compiler flags, and OS release." Yager put this matter to AMD's performance engineers and was told he was seeing an effect widely known among CPU engineers, but seldom communicated to IT - that the performance envelope of a CPU is cast in silicon, but is sculpted in software. "Long before you lay hands on a server," Yager writes, "BIOS and OS engineers have reshaped its finely tuned logic in code, sometimes with the real intent of making it faster [...] sometimes to homogenize the server to flatten its performance relative to Intel's."